The invention is directed to a method for the transmission of location data and measurement data from a terminal unit, especially a telematic device, to a central traffic control.
The use of vehicles driving along in traffic in a traffic network for the purpose of acquiring traffic data (FCD=floating car data) for a traffic detection and forecast center requires transmission of data from the vehicle to the traffic forecast center via mobile radio or the like. In so doing, a vehicle (FC) transmits to a central traffic control data implicating the location of the vehicle at a plurality of successive points in time, possibly including data impliciting each point in time, as well as measurement data detected by the vehicle, for example, speeds, average speeds for a trip, temperatures and the like, at determined points in time at determined locations or between determined locations at which the terminal unit is located at these points in time. However, the telecommunications costs entailed in the transmission from the terminal device to a central traffic station are relatively high.
The object of the present invention is to reduce the telecommunications costs in the transmission of data from a terminal unit to a central traffic station in a simple, economical and efficient manner.
The invention leads to a reduction in occurring telecommunications costs. Location data impliciting the location of the terminal unit in a traffic network at a respective point in time and measurement data impliciting characteristics of the traffic network at a location and/or at a point in time are transmitted from the terminal unit independently from one another. In this respect, location data on the one hand and measurement data on the other hand can be combined prior to a transmission to form location data records and measurement data records which contain a measurement datum or a location datum or measurement data and location data at different locations and points in time. In particular, characteristics of the traffic network at a location and/or at a point in time which are implicited by measurement data may be data indicating a backup and/or a travel time and/or a possible driving speed and/or a temperature and/or precipitation at a location and/or the point in time of a location (of a vehicle) in the traffic network. The location may be indicated by a determined location point or by a location area (that is, a partial section within the traffic network) which is indicated, for example, by several points. The time to which characteristics of the traffic network implicited by measurement data can refer, for example, may be indicated by a point in time or by a time range in the form of a plurality of points in time. Data records with measurement data can contain a reference datum of a given type for correlating the measurement data in the central station to a position, for example, in a digital map of the traffic network; a referencing of this type can relate to the location of the traffic network and/or to the point in time to which the measurement data relate based on their measurement. A terminal unit according to the invention can be, for example, a telematic device for a vehicle, which telematic device can be constructed for detecting traffic data and/or receiving traffic data from a central traffic station.
With respect to transmission from a terminal unit to a central traffic station, the method according to the invention enables optimum utilization of cost-intensive telecommunications times, whose availability may also possibly be limited. The total amount of data to be transmitted is reduced through the mutually independent compression and transmission of data records containing only location data and data records containing measurement data. Moreover, it is possible to adapt to local requirements; for example, on a straight stretch of highway without exits or entrances, transmission of location data is useful or meaningful only at relatively long time intervals or spatial intervals, so that, in this case, possibly more measurement data (about speeds, backups, icy roads, etc.) than location data may be transmitted. On the other hand, in an urban area, for example, it may be advisable to transmit location data at short time intervals and/or spatial intervals because there is a relatively large number of possible turns for the vehicle which require a relatively frequent transmission of location data for complete detection of the path of the vehicle in the city, so that in this case possibly more location data than measurement data must be transmitted. However, individual data records can contain location data and measurement data at points in time when location data and measurement data for transmission occur.
The length of a data record containing only location data and/or of a data record with measurement data advisably varies. The location referencing and time referencing of data records with respect to location data and of data records with respect to measurement data can differ. In particular, referencing can relate to a location or point in time or a location area or time range. The transmission is advisably carried out by mobile radio. The transmission of data records from the terminal unit to the central traffic station as a short message (e.g., GSM SMS), which allows extensive universality and automatic further processing in the central traffic station is particularly advantageous.
The times when data records with location data and/or with measurement data are transmitted can be defined by different, predeterminable conditions in the terminal unit: a transmission of measurement data records from the terminal unit to the central traffic station can be carried out when an event of a type predetermined in the terminal unit takes place. In particular, an event of this kind can take place when the speed of the vehicle in which the terminal unit is located falls below a speed value, when falling below or exceeding one of several speed values, when driving along a sharp curve (with a sharp turning of the steering wheel and/or a change in the driving direction of the vehicle in which the terminal unit is located, which change is detected by GPS), at the expiration of a time interval (after which a transmission of measurement data must take place), or the like, in order to enable automation.
The transmission of a location data record can be carried out at the expiration of a defined time interval and/or at the occurrence of another event. Accordingly, location data can also be transmitted, for example, when a vehicle containing a terminal unit passes a given location (out of a plurality of predeterminable locations), that is, for example, a determined highway junction. In this respect, the passing of a determined location can take place based on a digital map in the terminal unit and/or based on the position of the terminal unit detected by GPS or the like. In addition to this or instead of this, a transmission of location data from the terminal unit to the central traffic station is also useful when the vehicle in which the terminal unit is located has traveled over a certain section or when a change in direction has been carried out (which can be detected by a turning of the steering wheel and/or by continued location detection in the terminal unit) because it is important precisely in this case to transmit a new location data record for determining the path of the terminal unit for the central traffic station.
The method according to the invention can be implemented in a terminal unit and/or in a central traffic station.
Further features and advantages of the invention are indicated in the following description of an embodiment example with reference to the drawing.